The Defiler

The most well-known eldritch deity is called many many things, but by its actual followers is called the Great Progenitor or the Primogenitor. Most non-demons call it the Defiler. There are a lot of glorifying and condemning epithets attached to this one by its adherents and its opponents. The Defiler can be seen as an autonomous entity (usually by its worshippers) or, unlike the other gods, as a mindless, agenda-less, immutable spawn point for eldritch energy.